54) In isometric drawing, the three mutually perpendicular edges of a cube are at an angle of A. 120 degree B. 90 degree C. 18 degree Which of the above given is/are correct?

55) The sharp corners of the bolt head and nut are chamfered at _____ degree to the flat faces.

56) A _____ view will be useful as a guide in assembling the part of the machine itself.

57) Transformer tank is not filled with water because